Dermatoglyphics, the development and final configurations of digital and palmar dermal ridges have proven to be excellent biological markers. While they are for the most part genetically determined, their final development, which is completed at the end of the first trimester of pregnancy, is also influenced by intrauterine disturbances. Once developed, dermatoglyphics do not change nor can they be altered. No two individuals (including identical twins) have identical dermatoglyphics. These qualities make dermatoglyphics very useful genetic, as well as early prenatal environmental markers in clinical studies. This project represents an ongoing collaborative effort, involving WHO and other national and international laboratories to coordinate the collection, evaluation and interpretation of normal genetic markers. Specifically, the objectives of this project are: (A) To study the distribution of Dermatoglyphic markers in population isolates, family units, disease entities and normal control samples, and to utilize these genetic markers in understanding the etiology, development and early diagnosis of diseases or processes with late onset. (B) To determine the lateral functional dominance, grip strength, among BLSA participants, and assess their relationship to physiological processes or diseases demonstrating bilateral asymmetry. (C) Cross-sectional and longitudinal study of visual function in BLSA participants.